深入解析golang bufio

	tr := &http.Transport{
		WriteBufferSize:     64 * 1024,
	}

	pconn.br = bufio.NewReaderSize(pconn, t.readBufferSize())
	pconn.bw = bufio.NewWriterSize(persistConnWriter{pconn}, t.writeBufferSize())

type Writer struct {
	err error
	buf []byte
	n   int
	wr  io.Writer
}

type Writer int
func (*Writer) Write(p []byte) (n int, err error) {
	fmt.Printf("Writing: %s\n", p)
	return len(p), nil
}
func main() {
	w := new(Writer)
	bw1 := bufio.NewWriterSize(w, 4)
	// Case 1: Writing to buffer until full
	bw1.Write([]byte{'1'})
	bw1.Write([]byte{'2'})
	bw1.Write([]byte{'3'})
	bw1.Write([]byte{'4'}) // write - buffer is full
	// Case 2: Buffer has space
    bw1.Write([]byte{'5'}) //此时buffer中无法容纳更多的数据，执行写操作，写入 []byte{'1','2','3','4'}
	err = bw1.Flush() // forcefully write remaining
	if err != nil {
		panic(err)
	}
	// Case 3: (too) large write for buffer
	// Will skip buffer and write directly
	bw1.Write([]byte("12345")) //buffer不足，直接执行写操作
//结果：
Writing: 1234
Writing: 5
Writing: 12345

wr := new(Writer)
bw := bufio.NewWriterSize(wr,2) 
bw.Reset(wr) 

type Reader struct {
	buf          []byte
	rd           io.Reader // reader provided by the client
	r, w         int       // buf read and write positions
	err          error
	lastByte     int // last byte read for UnreadByte; -1 means invalid
	lastRuneSize int // size of last rune read for UnreadRune; -1 means invalid
}

func (b *Reader) Read(p []byte) (n int, err error)

func (b *Reader) ReadSlice(delim byte) (line []byte, err error) 

r := strings.NewReader("1234,567")
rb := bufio.NewReaderSize(r, 20)
fmt.Println(rb.ReadSlice(','))
// 结果：[49 50 51 52 44] <nil>

ReadLine() (line []byte, isPrefix bool, err error)

func (b *Reader) ReadBytes(delim byte) ([]byte, error)

    rb := strings.NewReader("12345678901234567890")
	scanner := bufio.NewScanner(rb)
	for scanner.Scan() {
		fmt.Printf("Token (Scanner): %q\n", scanner.Text())
	}
	// 结果：Token (Scanner): "12345678901234567890"